Gas monitoring instruments, also known as gas detection units, are used in a wide variety of different fields to detect the presence of a gas in a particular amount. In some instances, the gases being monitored are hazardous in nature so that their presence in a particular area can pose a significant health risk to anyone exposed to the gases. The monitoring of such gases falls within the field of industrial hygiene and includes, for example, monitoring or detection of the accumulation of carbon monoxide in underground parking garages or the accumulation of gases in underground mines, manholes, or other confined spaces. Gas monitoring instruments are also used as breath alcohol analyzers, for example by police forces in order to determine whether or not a person has been drinking and their level of intoxication. In each of these cases, it is important to be able to detect the presence of the gas as well as levels of the gas, including potentially harmful levels. Therefore, it is critical to make certain that the gas monitoring instrument functions properly and gives an accurate reading since failure to provide an accurate reading could result in adverse situations such as a fatality caused by excess exposure to toxic/hazardous gases or injury caused by the inability to confirm whether or not a person has been drinking.
In order to assure that an instrument detects gas levels accurately and reliably, it is necessary to test the instrument with a known concentration of gas. By exposing the instrument to a known concentration of gas, it is possible to determine not only the accuracy of the instrument but also whether the instrument is functioning properly. This testing includes, for example whether specific alarms or indicators are also functioning properly in gas monitoring instruments used in industrial hygiene and the accuracy of the instrument in breathalyzers. This testing is often referred to as “calibration”. In addition to calibration, people often utilize what is referred to as a “bump” test for testing the accuracy of an instrument. As used herein the term “bump test” refers to a brief exposure (or bump) of the instrument with a known concentration of gas/gases for the purposes of determining whether or not the instrument is functioning properly.
It is also necessary to calibrate/bump test instruments to rule out situations that involve false negatives. For example, when an instrument has lost its sensitivity to a target gas, it may give a reading of zero which would be the same reading that would be given in the absence of any gas. Accordingly, a large number of industries now recommend more frequent calibration/bump testing of instruments.
Original equipment manufacturers (OEM's) often manufacture instruments that can regulate or meter gas flow. While these instruments do require a regulator, a regulator is typically an accessory to the system. These instruments are also limited to calibrating the OEM's own devices. In addition, the instruments are bulky and therefore not portable. In most cases, they are operated by proprietary software and powered via an AC cord. In the industrial hygiene market, expensive automatic calibration stations and or bump test stations are often used. These are instruments that are peripheral to the regulator and cylinder package and are usually computer controlled. They are also not portable and require proprietary software to dispense the calibration gas.
There are also a variety of additional apparatus on the market which provide calibration/bump testing abilities. However, these apparatus are also very bulky and cumbersome. As a result, they are very difficult, if not impossible, to transport in the field and as a result must be mounted at a stationary station. As used herein, the phrase “in the field” refers to the main area where the gas monitoring instruments are used. For example, “in the field” would refer to “in mines” for gas monitoring instruments used to detect toxic/hazardous gases in mines while “in the field” would refer to “in police vehicles” for gas monitoring instruments used to detect breath alcohol levels. The result is that any instrument needing calibration/bump testing must be brought to this stationary station (to the calibration/bump testing apparatus) rather than having the apparatus be available at the site where the instrument is located or at the site where the instrument is used. As a result, these encumbrances place a limit on the degree of calibration/bump testing that can be conducted since it is necessary to bring the gas monitoring devices to the calibration apparatus rather than carry the calibration apparatus to the people in the field.
In addition, with regard to the prior art apparatus that are currently on the market in the form of stationary stations, there is a high degree of human involvement with regard to these calibration/bump testing apparatus. In many instances, for example, in the field of breath alcohol testing, mechanical preset flow regulators are used to calibrate the portable breathalyzer devices (also commonly referred to as breath alcohol instruments). These regulators all have mechanically controlled mechanical activation buttons or knobs (hand trigger release devices) which have to be pushed and/or held down for a prescribed period of time in order to allow the gas to flow from the calibration gas source to the instrument that is to be calibrated (the gas monitoring instrument). The person using the device must begin counting the predetermined seconds set forth by the manufacturer while holding down the button in order to calibrate/bump test the device. For example, if seven seconds are required for the calibration/bump testing, then the user must push in the button and hold it while they count to seven seconds. During this period of time in which the activation button or knob is pushed in, the valve is opened and gas will flow into the instrument at a given flow rate to approximately the desired volume (flow rate plus time used to dispense a particular volume of gas) before the valve is manually closed. Due to inaccuracy on the operator's part, the result could be the operator holding down the button for less than the necessary time, thereby leading to an insufficient volume of calibration gas being passed to the instrument to be calibrated, or holding down the button for too long thereby leading to an excess amount of calibration gas being passed to the instrument to be calibrated. As is evident, there is great room for human error using such an apparatus.
An unpublished study examining the use of hand trigger release devices showed a 30% error existed between people counting to two seconds and an 20% error existed between people counting to six seconds. In many instances such an error would be considered sufficient to call into question the accuracy of the results obtained especially when considered in cases involving the use of breath alcohol analyzers. In addition to the question of accuracy, often the operator is not getting the maximum cycles from the calibration gas source due to the human error on the part of the operator. In other words, the calibration gas is being wasted.
As a result, there exists a need for an apparatus that can be used in the field for calibration/bump testing of a gas monitoring instrument which overcomes the above noted problems. More specifically, there exists a need for an apparatus for calibration/bump testing that is portable, easy to use, and economical. There also exists a need for a portable apparatus that eliminates the human error associated with calibration/bump testing, thereby resulting in a more reliable and accurate readings for gas monitoring instruments.
In view of the above, it is the objective of the present invention to provide a portable, easy to use, economical, reliable and accurate apparatus and process for calibration/bump testing of a gas monitoring instrument by precisely and accurately dispensing a specific volume of a known calibration gas from a calibration gas source.